The invention concerns a lighting strike protection means for applying automatically to a fiber composite component and a fiber composite component with a lightning strike protection.
In modern aircraft construction components that are manufactured with fiber-composite plastics are widely deployed. In the structural regions of aviation vehicles carbon fiber-reinforced thermosetting plastics are primarily deployed, wherein carbon fiber-reinforced thermoplastic high-performance plastics are also encountered to some extent. Furthermore other reinforcing fibers, such as, for example, glass fibers, Kevlar® fibers, or Aramid® fibers, can be deployed. With the deployment of fiber composite plastics a considerable potential for weight saving ensues; amongst other factors this leads to increased ranges by virtue of reduced fuel consumption. Furthermore in comparison to the metallic materials, in particular the aluminum alloys, for a long time customary in aircraft construction, plastic materials have excellent corrosion and fatigue resistance, as a result of which the servicing and maintenance effort can be significantly reduced in the operation of such aircraft.
By virtue of the generally significantly lower electrical conductivity of the fiber composite plastics compared with metallic materials, additional measures must be taken, in particular for lightning strike protection and earth return paths for the on-board electrical systems. The earth return paths are achieved, for example, by means of additional copper lines with large cross-sections, while the lightning strike protection is achieved by means of metals integrated into the external surfaces of the structural components. At the present time structural components, such as, for example, shell modules for fuselage sections, are often produced with the aid of the so-called ATL-method (“Automated Tape Laying”). In the tape laying process prepreg materials having the shape of tapes, in particular carbon fiber tapes, that are preimpregnated with a resin and that have a common width from 75 mm to 300 mm are laid down in an automated manner by means of a suitable device on a form-defining molding tool in various spatial directions, until the fiber composite component that is being manufactured has achieved a prescribed material thickness in all regions.
An alternative laying method is the so-called AFP-method (“Automated Fiber Placement”). In the fiber placement process prepreg materials, in particular carbon fiber strands or carbon fiber bundles that normally are ⅛″ to 1″ wide are laid down automatically. Alternatively, the prepreg materials are replaced by dry fiber strands or dry fiber bundles.
Due to the enhanced width of the tapes to be laid down, the ATL-method is used basically for slightly curved or flat surfaces, while the AFP-method is preferred for more complex geometries.
In the procedures of previous known prior art, lightning strike protection means are manually applied before or after the fiber tapes have been laid down. For this purpose a ribbon-form copper foil is laid down and pressed down on load-bearing material in the form of overlapping widths. With the application of pressure and/or temperature, for example by means of a vacuum bag procedure in an autoclave, the construction is then cured to form the finished fiber composite component.
In the patent application WO 2010/135318 A2 a method for automatically laying down a lightning strike protection means is shown. The lightning strike protection means has a metal strip and a bendable reinforcement structure for stabilizing the metal strip during the automated laying process. The reinforcement structure is attached to the metal strip over the entire length and has the same width as the metal strip.